The most common and most likely answer to this crossword clue is the 9 letter word RECEIPTED
I've seen this crossword clue in Independent
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Buddy explains!
The straight part
We know that "Marked as having paid" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case marked as having paid = receipted.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does RECEIPTED mean?
RECEIPTED verb- To give or write a receipt (for something).
- To put a receipt on, as by writing or stamping; to mark a bill as having been paid.